def isPortFree(port) {
    def serverSocket = null
    try  {
        serverSocket = new ServerSocket(port);
    } catch (IOException e) {
        return false
    } finally {
        if (serverSocket != null) {
            serverSocket.withCloseable {
                // deliberately empty
            }
        }
    }
    true
}

def isPortFree(port) {
    def serverSocket = null
    try  {
        serverSocket = new ServerSocket(port).withCloseable { };
    } catch (IOException e) {
        return false
    }

    return true
}